Apparatus for helically corrugating flexible tubular metal foil ducts

ABSTRACT

A fluted mandrel rotates within a flexible, axially moving, metal foil, corrugated tubular duct as it is being continuously formed, downstream of the corrugation forming dies to remove burrs from the internal surfaces created during wrapping of the foil strips to form the tube and corrugation of the same to lower resistance to air flow through the tubing during usage.

United States Patent Amos et al.

1 Aug. 22, 1972 154] APPARATUS FOR HELICALLY CORRUGATING FLEXIBLETUBULAR METAL FOIL DUCTS [72] Inventors: Charles William Amos; MaynardDale Johnson, both of Harrisonburg; John Jacob Dieckmann, RockinghamCounty, all of Va.

[73] Assignee: Dunham-Bush, Inc., l-larrisonburg,

22 Filed: March 18, 1971 21 Appl.No.: 125,677

[52] US. Cl ..72/129, 72/135 [51] Int. Cl....; ..B21C 37/12 [58] Fieldof Search ..72/135, 41, 45,43, 44,70, 72/71,129,130,137,138,141, 340,341,

' [56] References Cited UNITED STATES PATENTS 2,351,710 6/1944 Sanders..72/41 2,688,906 9/1954 Dokopil ..156/207 X 3,528,159 9/1970 Miles..29/423 Primary Examiner-Richard .1. Herbst Attorney-Sughrue, Rothwell,Mion, Zinn & Macpeak [57] ABSTRACT A fluted mandrel rotates within aflexible, axially moving, metal foil, corrugated tubular duct as it isbeing continuously formed, downstream of the corrugation forming dies toremove burrs from the internal surfaces created during wrapping of thefoil strips to form the tube and corrugation of the same to lowerresistance to air flow through the tubing during usage.

5 Claims, 3 Drawing Figures APPARATUS FOR HELICALLY CORRUGATING FLEXIBLETUBULAR METAL FOIL DUCTS BACKGROUND OF THE INVENTION 1. Field of theInvention This invention relates to machines for automatically formingflexible tubular ducts by helically overlapping metal foil strips andmore particularly to an improved apparatus for forming the same in whichthe tubing is corrugated without materially increasing its resistance tothe passage of air flowing through the same during usage.

2. Description of the Prior Art Machines have been developed for theproduction of helically corrugated flexible tubular metal ducts in longcontinuous lengths, which are substantially air tight for use in airconditioning installations. Such a machine is set forth in US. Pat. No.3,528,159 to George N. Miles and entitled Method of Making HelicallyCorrugated Flexible Tubular Duct of Metal Foil and for Insulating theSame.

In the referred to patent, the corrugated, flexible duct is formed byfirst helically wrapping a strip of friction reducing material, such asa paper tape on the exterior of a fixed hollow forming mandrel whichdefines a temporary inner surface of the duct wall. Secondly, aplurality of over-lapping strips of metal foil are helically wrappedupon the friction-reducing wrapping to define a duct wall havingmultiple plies of metal foil. Thereafter, the formed tube of metal foiland underlying paper is moved axially through simultaneously revolvinginner and outer, mating screw-threaded dies to create helicalcorrugations while at the same time continuously feeding the ductdownstream by the screw action of the revolving dies. One function ofthe inner paper lining is to reduce the friction between the formed tubeand the corrugating die. Also, oil is sprayed onto the outer surface ofthe helically wrapped metal foil tube just upstream of the corrugatingdies to further reduce the friction existing between the tubing and thedriven corrugating dies.

While the initial wrapping of the mandrel upstream of the corrugatingdies with paper acts to materially reduce the friction between themulti-ply metal tube and the inner corrugating die during manufacture,it is necessary to remove the inner paper layer of the tube downstreamof the corrugating means to produce a wholly metal corrugated tubeuseful in passing air under pressure and at high velocity and suchhelically corrugated metal foil tubes have great application to the airconditioning industry.

In the Miles patent, means are provided for unpeeling the helicallywrapped paper layer from the internal surface of the multi-ply metalfoil tubing downstream of the corrugating dies and, in fact, downstreamof a stationary holding assembly which prevents the tube from twistingdue to the effects of the corrugating dies. The holding assembly liesintermediate of the corrugating dies and corrugation stretching means inthe form of a plurality of reciprocating fingers which act to stretchthe tube corrugations at the output end of the machine. ln the Milespatent, in order to prevent the paper stripping means from stripping thepaper prior to passage beyond the holding assembly and the corrugatingstretching means, a magnetic sensor is employed which senses the changein reluctance of the magnetic circuit due to the presence or absence ofthe paper and the magnetic sensing means is located just downstream ofthe stretching assembly. This achieves periodic energization of afriction clutch controlled paper pulling apparatus at the extremeupstream end of the machine associated with a windlass mechanism, withthe removed paper strip falling freely into a waste area at the frontend of the machine.

While satisfactory, use of the paper itself increases the cost of theproduction of the flexible, corrugated metal foil duct, adds to thecomplexity of the machine and increases maintenance time and thepropensity for machine shutdown due to the necessity for adjustment ofassociated elements or replacement due to' their failure.

In an attempt to eliminate the necessity for preliminary formation of aninner paper lining for the multiply metal foil duct prior tocorrugating, the initial helical wrapping of the paper foil to themandrel upstream of the corrugating dies was eliminated but thisresulted in an increase in friction between the helical metal foil ductand the inner rotating corrugating die and, more importantly, caused theformation of burrs on the internal surfaces of the corrugated metal foiltubular duct.

SUMMARY OF THE INVENTION The present invention is directed to animproved machine for making helically corrugated, metal foil flexibletubular ducts in which the need for initially wrapping the duct-formingmandrel upstream of the corrugating die with a paper lining, iseliminated. Further, the improved machine of the present inventionallows a flexible tubular duct to be formed without this preliminarystep and without materially increasing the friction between the rotatingcorrugating dies and the duct and allows the tubular duct to becompleted without internal burrs sufficient to materially affect thestatic pressure of fluids passing through the same during usage.

Specifically, the present invention is directed to an improved machinefor forming a flexible tubular duct having a helically corrugated metalfoil wall of the type employing a hollow mandrel upon which is wrapped aplurality of strips of metal foil to define a multiple ply duct wall.Inner and outer corrugating dies downstream of the hollow mandrelembrace the helically wound metal foil duct to corrugate the same whileautomatically feeding the duct axially. The machine further includesmeans exterior of the corrugations for axially spacing the corrugationsdownstream of the corrugated forming dies. Lubricating oil is sprayedonto the inner and outer surfaces of the helically wound multi-ply metalfoil duct upstream of the corrugating die for reducing friction duringcorrugating. A mandrel is rotated internally of the duct downstream ofthe corrugating means, the rotating mandrel being fluted to definelongitudinal cutting edges capable of deburring the internal surfaces ofthe corrugated metal foil tubular duct during continuous production ofthe duct and axial movement of the duct about the rotating mandrel.

Preferably, the rotating mandrel includes a plurality ofcircumferentially distinct flexible fingers defining the fluted portionof the mandrel and carries an axially threaded bore a portion of itslength which threadably receives a tapered adjusting screw permittinglimited fingers to vary first helically wrapped, and is preferablycoupled to a.

drive motor through a suitable gear reduction, speed control mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view,partially broken away, of the improved apparatus of the presentinvention.

FIG. 2 is a sectional, elevational view of a portion of the apparatusshown in FIG. 1.

FIG. 3 is a section of the rotating mandrel forming a major element ofthe improved apparatus of the present invention, taken about lines A-Aof FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, theapparatus of the present invention constitutes a machine comprising ametal mainframe 1 which is U-shaped in configuration and incorporates apair of upright support members 2 and 3 which encloses portions of thedrive mechanism and supports in particular a fixed, hollow mandrelassembly identified generally at 4. A main drive motor 6 rests on thefloor of the building housing the machine and through a belt and pulleydrive arrangement, rotates a counter shaft 7 which is in turn supportedby bearings 8 at opposite ends of the machine main frame 1. The countershaft 7 carries two sprockets 9 and 11 at opposite ends of the frame 1with a change-gear box 12 providing a driving connection between thecounter shaft 7 and a stub shaft 16 which in turn drives a sprocket inthe opposite direction to that of sprockets 9 and 11. Sprocket chains13, 14 and 15 respectively coupled to sprockets 9, 10 and 11 engagerespective sprockets 17, 18 and 19 carried by the mandrel assembly 4. Byshifting gears in box 12 the speed of rotation of sprocket 18 may bevaried relative to the speed of rotation of sprockets 17 and 19. A drivepath, including sprocket 9, chain 13 and driven sprocket 17, rotates ahollow shaft 20 which is coaxially positioned within a fixed, hollowmandrel 33 forming a part of the mandrel assembly 4. The driven hollowshaft 20 is attached by a disengagable positive drive connection 22 tothe inner helical screw-threaded, hollow corrugating die 23, FIG. 2, insuch a manner that die 23 is rotated due to the connection 22 beingformed by projecting dogs on the rear face of the inner die 23 whichengage in recesses in the end of the hollow drive shaft.

ln mesh with the inner die 23 is an outer helical screw-threadedcorrugating die 24, which seats in a socket 25 within hub 26 of drivensprocket 19. The outer die 24 is keyed to the hub 26 to be positivelydriven by the drive path including driving sprocket l1, sprocket chain15, driven sprocket 19 and hub 26. The

sprockets 9 and 11 are of thesame diameter as are sprockets l7 and 19,thus the inner and outer corrugating dies 23 and 24 rotate at exactlythe same speed to helically corrugate the tabular wall 27 of a multi-plymetal foil duct 28, FIG. 1, while feeding the duct from right to leftby. the screw action of the mating dies as indicated by arrow 30.

The dies 23 and 24 are readily removable by pulling them from right toleft, FIG. 1, thus simultaneously disengaging them respectively fromshaft 20 and from hub 26. After the dies 23 and 24 are removed, they maybe separated from each other by the simple act of unscrewing one fromthe other.

As described to this point, the apparatus is identical to that of theMiles patent and to form the metal foil duct, a spool assembly 32 isrotated by the driven sprocket l8 joumaled by the main frame 1 about thehollow, fixed forming mandrel 33, which in turn is concentric with andsurrounds the rotating hollow shaft 20. A pair of strips of metal foil34 and 36, preferably of aluminum and having a thickness on the order of0.003

inches, are fed from respective spools carried by the spool assembly 32to form, in terms of a left hand helical wrap, the duct wall 27 in theidentical manner to that of the referred to patent. As readily indicatedby the relative size of the sprockets l0 and 18, FIG. 1, the spoolassembly 32 rotates at about one-half the r. p. m. of dies 23 and 24,the relative rate being determined by the pitch at which the foil strips34 and 36 are applied.

Unlike the prior art machine, in order to reduce friction between theouter die 24, the inner die 23 and the multi-ply foil tube sandwichedtherebetween and corrugated by rotation of both dies, an oil spray mistapplied by an air driven oil atomizer spray nozzle 40, FIG. 1, exteriorof the mandrel assembly 4 and upstream of the dies 23 and 24, and asimilar device (not shown), interiorly of mandrel 33, allows the innerand outer surfaces of the wall 27 to be lubricated sufficiently togreatly reduce the friction between the dies and the aluminum wall 27.During operation, dies 23 and 24 corrugate the wall 27 with closelypacked corrugations in a right hand helix.

In order to prevent the tubular wall 27 of duct 28 from turning, astationary holding assembly 42 is employed downstream of the corrugatingdies 23 and 24 which is modified slightly from that of the prior artpatent. The holding assembly, in similar fashion to the prior patent,includes a pair of concave cylindrical gripping jaw members 43 which areremovably connected to a pair of arms 44 pivotably attached at 45 to amounting plate 46 which is in turn secured by bolts 47 to support 2 offrame 1.

A tension spring 48 positioned between arms 44 urges the arms towardeach other to press the jaw members 43 against the outside of thetubular wall '27. Means (not shown) allow the arms 44 to be swungoutwardly allowing the jaw members 43 to be readily removed in theidentical fashion to the prior art patent.

Unlike the prior art patent, the holding assembly 42 includes anon-adjustable inner, stationary arbor or mandrel 52 whose circumferencemay or may not be longitudinally fluted depending upon the necessity toreduce friction between the stationary components of the machine and thehelically moving duct 28 downstream of the corrugating dies. Asillustrated, the

arbor 52 comprises a hollow cylindrical mandrel 204 which has a threadedaxial bore section 53 allowing it to threadily engage the outer end of ahollow stationary shaft 58 which is coaxial with the hollow rotatingshaft 20, the rotating shaft being concentric to the fixed shaft 58.Shaft 58 extends towards the front of the machine, is joumaled by theright hand upright support 2 of the main frame 1 and is fixed to theframe by a spider assembly 54 which replaces the windlass of the priorart machine. The diameter of the fixed mandrel 204 is generally the sameas the desired internal diameter of the helically corrugated duct 28 andthe frictional restraint provided by the gripping jaw members on theexterior surface is sufficient to allow feed of the tubular duct 28axially in the direction of arrow 30 but prevents rotation of the sameduring corrugating.

In a similar manner to the prior art machine, an axially slidable,reciprocating slide assembly 60 is provided on the left hand end of themachine, FIG. 1, with the assembly 60 being mounted on a pair oflongitudinally extending slideways or rods 61 fixed t0 the main frame 1by means of plate 46. To effect reciprocation of assembly 60, a push rod62 is pivotably attached to the arm of lever 63, the lever being pivotedon the same mounting plate 46 and being coupled at another arm to aconnecting rod 64 by adjustable coupling means 65. In turn, theconnecting rod 64 is carried by revolving crank 66 at the outboard endof counter shaft 7. Adjusting connection 65 varies the length of thestroke of the reciprocating assembly 60.

The assembly 60 includes a pair of side plates 68, to each of which isattached, a plurality of longitudinally spaced, spring rachet fingers 70which converge in a downstream direction with duct wall 27. The innerends 71 of the spring fingers are bent inwardly and at generally rightangles to the axis of duct 28 and preferably'shaped with a concave endsurface adapted to engage the outside of the duct wall 27 in the valleysbetween successive convolutions as shown in FIG. 2. The outer ends 73 ofthe spring fingers are secured to the side plate 68 by bolt 74. Withthis arrangement, when the slide assembly 60 moves downstream, that is,from right to left, FIG. 1, the finger ends 71 engage in the valleys andpull the localized region of the duct axially to space the convolutionsof the corrugated duct further apart. When the slide assembly 60 moveson reverse motion, toward the right, the spring fingers 70 flexoutwardly so that their ends 71 slide over the ridges of theconvolutions. The stretching, hitch feed action of the multiple fingers70 occurs at an average feed rate greater than the screw feed rate ofdies 23 and 24 so that the net effect is to stretch open thecorrugations formed by the dies. For access to the formed tubular duct28, the slide assembly 60 may be opened up quickly by rotation of latch77 from the horizontal position shown, FIG. 1, thus allowing the sideplate 68 to be swung outwardly about hingepins 78.

The present invention is directed particularly to a rotating mandrelassembly 200 which is in general lonmary function of deburring theinternal surfaces of the duct so as to greatly reduce the frictionefiects of the confining duct on a moving air stream within the ductduring normal usage in the refrigeration and other arts.

Specifically, the present machine carries a third rotatable, solid shaft203 about which fixed hollow shaft 58, rotating hollow shaft 20 andfixed hollow mandrel 33 are concentrically positioned in that order. Therotating shaft 203 extends the full length of the machine and isthreadably coupled, at its downstream end, to a cylindrical mandrel 202.At its upstream end, the shaft 203 is joumaled within spider assembly54, the extreme outer end protruding outwardly from the spider and iscoupled to a sprocket wheel 205. An auxiliary motor 208 mounted on afixed support 210 which, in turn, is coupled to spider 54 has its outputshaft 211 coupled to a gear box 208. ln turn, the gear box has an outputshaft 212 carrying a driving sprocket 207, the driving sprocket beingcoupled to driven sprocket 205 via endless drive chain 206.

While the portion of the rotating mandrel 202 which lies interior of thereciprocating stretching assembly has a smooth unbroken peripheralsurface and acts as a full circumferential support for the formedtubular duct 28 in the area of the stretching mechanism, the mandrelterminates at its downstream end in a fluted portion 202. The flutedportion is defined by slightly flexible fingers 213 spacedcircumferentially at 90 and being separated from each other bylongitudinal slots 214 which extend the length of the fluted portion202'. This end of the mandrel 202 is tapped and threaded at 215 andreceives an adjustment screw 201 which is provided with a slightlytapered thread. Thus, by rotation of the adjustment screw 201, theindividual fingers 213 are spread radially causing longitudinalcuttingedges 216 of the rotating mandrel 202 to contact the interior surfacesof the corrugated tubular duct 28. The speed of the rotating mandrel 202may be readily varied by change speed box 208 and/or by the selection insize of the driving sprocket 207 and the driven sprocket 205, however,it is preferable that the rotating mandrel 202 be driven at a speed inexcess of and rotate in the opposite direction to the corrugating diesto insure maximum deburring of the interior surfaces of the formedmulti-ply metal foil corrugated tubular duct 28.

The operation of the machine is apparent from the previous description.However, briefly, the machine is quite capable of producing a corrugatedall-metal duct 28 at a rate of 12 lineal feet per minute with thecorrugating dies 23 and 24 revolving at approximately 300 r. p. m. andthe spool assembly revolving at a rate of approximately one-half thesame. Aluminum foil strips of 0.003 inches and a width of two andone-half to three inches produces a finished corrugate duct having awall thickness of approximately 0.08 inches including the depth of thecorrugations with the duct being substan- 42. After the formed,corrugated tubular duct 28 slides between outer clamping member 43 andinner, fixed mandrel 204, the duct moves axially over the smoothcircumferential surface of the upstream portion of the rotating mandrel202. At this point, the flexible fingers 70 of the reciprocatingstretching assembly 60 engage the outer surface of the duct and stretchthe individual convolutions, since reciprocation from right to leftoccurs at a greater speed than that of the moving duct as expressed bydies 23 and 24. In turn, during reciprocation from left to right, theflexible fingers move over the ridges and again fall into other valleysof the continuously moving duct 28. During the rotation of the mandrel202, the fluted portion 202' and in particular the longitudinal cuttingedges 216 of the individual fingers 213 rotate at relatively high speedwith respect to the nonrotating duct to deburr the interior surfacescaused by wrapping and corrugating of the multi-ply metal foil strips 34and 36. The finished duct 28 leaves the machine in a fashion capable ofbeing used with or without the addition of insulation material allowingthe manufacture of long lengths of insulated or noninsulated duct atminimum expense characterized by a smooth inner duct surface with lowstatic friction to the gases moving under pressure and at relativelyhigh velocity through the same during subsequent usage.

What is claimed is:

1. In a machine for forming a flexible tubular duct having a helicallycorrugated multi-ply metal foil wall including a hollow foil wrappingmandrel, means for helically wrapping a plurality of strips of metalfoil about said hollow mandrel in overlapping fashion to define amultiple-ply duct wall, relatively rotating inner and outer diesembracing said helically wound duct downstream of said wrapping meansfor corrugating the same and feeding the duct axially, the improvementcomprising:

a mandrel positioned internally of said corrugated tu bular duct,downstream of said inner and outer dies,

means for rotating said mandrel, and

longitudinal cutting edges carried by said rotating mandrel in contactwith the interior surfaces of said corrugated duct for removing anyburrs formed by passage of said multi-ply metal foil duct through saidcorrugating dies.

2. The machine as claimed in claim 1, wherein said machine furthercomprises means downstream of said corrugating ,dies operativelyengaging the exterior of said corrugated duct for axially spacing saidcorrugations and said rotating mandrel includes a peripheral surfaceportion radially aligned with said exterior corrugating spacing meansand in contact with the duct interior for supporting said duct duringexpansion of said corrugations by said axial spacing means.

3. The machine as claimed in claim 1, wherein said rotating mandrelincludes: a plurality of integral, circumferentially spaced, fingersdefining the fluted portion of said mandrel with edges of said fingersconstituting the longitudinal cutting edges of said mandrel and meanscarried by said mandrel allowing limited radial adjustment of saidflexible fingers to insure contactof said cutting edges with the ductinterior and maximum de 'n of same.

i flie mac ne as claimed in claim 2, wherein said rotating mandrelupstream portion which is radially aligned with said corrugationsconvolution spacing means is peripherally smooth and unbroken, and saidfluted downstream portion is defined by circumferentially spacedflexible fingers formed by longitudinal flute recesses, longitudinalslots at the bottom of said recesses, said rotating mandrel including anaxial bore extending from the downstream end a length on the order ofthat of said flute recesses and an adjustment screw carried by saidthreaded bore and having axially tapered thread portion wherebythreading of the screw deeper within the threaded bore of the mandrelforces the flexible fingers outwardly to increase the radial position ofthe longitudinal cutting edges and insure contact with the same with theformed tubular duct.

5. The machine as claimed in claim 1, wherein: said hollow foil wrappingmandrel is stationary and concentrically carries first, second and thirdshafts, said first shaft :is hollow, is mounted for rotation and isfixedly coupled to said inner die, said second shaft is hollow, iscoaxially fixed within said first shaft and extends axially downstreambeyond said inner and outer dies, said machine further includes: meansrotating said outer die at the same speed as said inner die to corrugatesaid tube, a fixed hollow stationary mandrel coupled to said secondshaft having a diameter on the order of that of said corrugated duct andpositioned downstream of the rotating die in contact with the interiorwall of said tube, clamping means-axially aligned with said fixedmandrel and frictionally gripping the outside of said corrugated tubularduct to prevent rotation of said duct during corrugation by said dies,means for supporting said third shaft for rotation within said fixedhollow second shaft with one end coupled to said rotating mandreldownstream of said fixed mandrel and said clamping means and the otherend extending axially beyond said fixed wrapping mandrel and beingcoupled to a drive motor for effecting rotation of said third shaft andthe rotating mandrel coupled thereto.

1. In a machine for forming a flexible tubular duct having a helically corrugated multi-ply metal foil wall including a hollow foil wrapping mandrel, means for helically wrapping a plurality of strips of metal foil about said hollow mandrel in overlapping fashion to define a multiple-ply duct wall, relatively rotating inner and outer dies embracing said helically wound duct downstream of said wrapping means for corrugating the same and feeding the duct axially, the improvement comprising: a mandrel positioned internally of said corrugated tubular duct, downstream of said inner and outer dies, means for rotating said mandrel, and longitudinal cutting edges carried by said rotating mandrel in contact with the interior surfaces of said corrugated duct for removing any burrs formed by passage of said multi-ply metal foil duct through said corrugating dies.
 2. The machine as claimed in claim 1, wherein said machine further comprises means downstream of said corrugating dies operatively engaging the exterior of said corrugated duct for axially spacing said corrugations and said rotating mandrel includes a peripheral surface portion radially alIgned with said exterior corrugating spacing means and in contact with the duct interior for supporting said duct during expansion of said corrugations by said axial spacing means.
 3. The machine as claimed in claim 1, wherein said rotating mandrel includes: a plurality of integral, circumferentially spaced, fingers defining the fluted portion of said mandrel with edges of said fingers constituting the longitudinal cutting edges of said mandrel and means carried by said mandrel allowing limited radial adjustment of said flexible fingers to insure contact of said cutting edges with the duct interior and maximum deburring of the same.
 4. The machine as claimed in claim 2, wherein said rotating mandrel upstream portion which is radially aligned with said corrugations convolution spacing means is peripherally smooth and unbroken, and said fluted downstream portion is defined by circumferentially spaced flexible fingers formed by longitudinal flute recesses, longitudinal slots at the bottom of said recesses, said rotating mandrel including an axial bore extending from the downstream end a length on the order of that of said flute recesses and an adjustment screw carried by said threaded bore and having axially tapered thread portion whereby threading of the screw deeper within the threaded bore of the mandrel forces the flexible fingers outwardly to increase the radial position of the longitudinal cutting edges and insure contact with the same with the formed tubular duct.
 5. The machine as claimed in claim 1, wherein: said hollow foil wrapping mandrel is stationary and concentrically carries first, second and third shafts, said first shaft is hollow, is mounted for rotation and is fixedly coupled to said inner die, said second shaft is hollow, is coaxially fixed within said first shaft and extends axially downstream beyond said inner and outer dies, said machine further includes: means rotating said outer die at the same speed as said inner die to corrugate said tube, a fixed hollow stationary mandrel coupled to said second shaft having a diameter on the order of that of said corrugated duct and positioned downstream of the rotating die in contact with the interior wall of said tube, clamping means axially aligned with said fixed mandrel and frictionally gripping the outside of said corrugated tubular duct to prevent rotation of said duct during corrugation by said dies, means for supporting said third shaft for rotation within said fixed hollow second shaft with one end coupled to said rotating mandrel downstream of said fixed mandrel and said clamping means and the other end extending axially beyond said fixed wrapping mandrel and being coupled to a drive motor for effecting rotation of said third shaft and the rotating mandrel coupled thereto. 